Apparatus for shellfish aquaculture

ABSTRACT

A pneumatically controlled shellfish aquaculture apparatus and method for growing shellfish using the apparatus are provided. A frame has containers for holding shellfish secured to the top side of the frame and tanks secured to the bottom side of the frame. Each tank has an air supply line connected to the tank and an opening on the bottom side of the tank. Each air supply line is connected to a manifold for controlling airflow to the tanks. Air is used to displace water in the tanks by pushing the water out of the openings in the bottom of the tanks in order to float the frame. To submerge the frame, the tanks are depressurized to allow water to displace the air in the tanks. When floating, the tanks lift the frame and the containers out of the water to allow air desiccation in order to prevent bio-fouling of the equipment and shellfish.

CROSS REFERENCES

This application is a continuation application of U.S. application Ser.No. 15/443,563, filed Feb. 27, 2017, which claims the benefit of U.S.Provisional Application No. 62/299,859, filed on Feb. 25, 2016, whichapplication is incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure refers generally to an apparatus and method forshellfish aquaculture.

BACKGROUND

It is estimated that over 90% of oysters, clams, and mussels producedfor consumption worldwide come from aquaculture farms. In particular,due to loss of wild oyster reefs, small-scale aquaculture of oysters hasincreased significantly in recent years. Typical shellfish aquaculturefarms utilize baskets, cages, trays, racks, or similar containers forholding the oysters either on the water bottom or off-bottom. Theoysters and aquaculture equipment remain submerged in natural waterbodies for extended periods of time during the growth of the oyster to amatured state suitable for harvest. During submerged periods, a biofilmof microorganisms may form on outer surfaces of the shellfish and thesubmerged aquaculture equipment, which can lead to the attachment ofnuisance bio-fouling organisms such as barnacles and unwanted bivalveshellfish. Bio-fouling organisms create nuisance by clogging mesh orpores in shellfish containers, which reduces water flow through thecontainers and food availability for the shellfish, thereby slowinggrowth of culture shellfish. Additionally, bio-fouling organisms attachdirectly to shellfish causing visual defects that reduce market value.Unwanted organisms also add excessive weight to the system and candamage moving parts of the aquaculture equipment. Periodic emergence ofthe equipment and shellfish in the air above the sea surface for about24 hours desiccates the biofilm before it sufficiently establishes topermit attachment of bio-fouling organisms. Emergence of the equipmenteliminates the need to pressure wash or clean equipment and shellfish byother means after bio-fouling organisms colonize the exposed surfaces.

In productive shellfish growing areas such as the Gulf of Mexico,desiccation of gear at weekly intervals is typically required to controlbio-fouling. Currently employed methods for bio-fouling control rely onintensive and potentially unsafe manual labor practices. Typicalaquaculture systems comprise rectangular containers constructed of heavyplastic coated wire mesh that are assembled with multiple containercompartments for holding flexible plastic mesh bags of varying meshsizes that contain shellfish at various growth stages. The containerstypically have two air-filled floats attached to the top of thecontainers on the outside edges on opposing sides to maximize stabilityto wave action. The air-filled floats provide adequate buoyancy to floatthe oyster-filled containers below the surface of the water for growingthe oysters. The normal bio-fouling practice employed with floatingaquaculture systems is to manually flip the containers upside down sothe floats are on the bottom of the containers. Float buoyancy elevatesthe oysters and the containers in the air above the water surface. Inshallow areas, flipping the containers is often done by wading, butboats are required to work deeper or colder waters. Relatively calmwaters are required to flip the containers from boats. After adesiccation period of about 24 hours, the containers are manuallyflipped back into the growth position until the next desiccationtreatment. This method of bio-fouling control is labor intensive andtime consuming, which drives up oyster production costs. In addition,there are safety risks involved with the manual flipping of theoyster-filled containers, which can be extremely heavy. To limit theweight, smaller containers or groups of containers must be utilized,thereby limiting the potential scale of an operation.

Accordingly, a need exists in the art for a shellfish aquacultureapparatus and method that allows for simple, fast, and safe bio-foulingcontrol.

SUMMARY

The shellfish aquaculture apparatus of the present disclosure automatesair desiccation of bivalve shellfish produced in off-bottomcontainerized aquaculture systems for the purposes of controllingbio-fouling on the surfaces of the shellfish and aquaculture equipment.In one aspect, a pneumatically controlled apparatus for shellfishaquaculture comprises containers secured to a top side of a frame and aplurality of tanks secured to a bottom side of the frame. In a preferredembodiment, the frame is rectangular and has a front end and a rear end.The apparatus preferably comprises four tanks positioned at the cornersof the frame. Two front tanks are positioned at the corners of the frontend, and two rear tanks are positioned at the corners of the rear end.Each tank has an air supply line connected to the tank and an openinglocated on a bottom side of the tank. Each air supply line may beconnected to a manifold for supplying air to each tank. The manifold hasa connection nozzle for a primary air supply line from an air source.The air source is preferably a pressurized tank, such as a SCUBA tank,or an air compressor. The manifold has valves for individuallycontrolling the flow of air to each of the tanks.

The shellfish aquaculture apparatus is configured for use in twopositions: a floating position and a submerged position. The tanks arefilled with air when in the floating position and with water when in thesubmerged position. When in the floating position, the containers andshellfish contained therein are lifted above the surface of the water.The containers and shellfish can be held in this position for a periodof time sufficient to allow air desiccation in order to prevent theformation of biofilm on the containers and shellfish, which is aprecursor to bio-fouling by barnacles or other unwanted organisms. Othershellfish husbandry activities such as stocking containers, size-sortingshellfish, grading, inspections to monitor the growth and quality of thestock, and harvesting are also facilitated while the apparatus is in thefloating position. Additionally, the apparatus can be disconnected frommoorings and towed away to avoid hazards or towed to a more favorablelocation for growth or acquisition of quality growth characteristicssuch as salinity. When in the submerged position, the tanks rest on thewater bottom and hold the containers and shellfish contained therein offthe water bottom to allow shellfish growth before harvesting.

To move the apparatus from the submerged position to the floatingposition, air is supplied to the tanks in order to displace the water inthe tanks. The air supply lines are preferably connected to the top sideof each tank, and pressurized air supplied via the lines displaces thewater in the tanks by pushing the water out of each respective openinglocated on the bottom side of each tank. As the water is displaced byair, the apparatus will rise to the surface of the water. Whensubstantially all of the water in each tank has been displaced by air,the apparatus will float on the surface of the water such that thecontainers and shellfish contained therein are above the water surface.

In a preferred embodiment, the process of filling the tanks with air todisplace the water is done in two steps. First, air is supplied only tothe two front tanks, which causes the front end of the frame to floatwhile the rear end of the frame rests on the water bottom. Next, air issupplied to the two rear tanks in order to float the rear end of theframe. The entire frame will then float and remain in the floatingposition as long as air pressure is maintained in the tanks. Filling thefront and rear tanks with air sequentially improves the stability of theapparatus and reduces the risk of flipping the frame and the containersholding shellfish during the process of filling the tanks with air tofloat the frame. The process of floating the apparatus is repeated eachtime bio-fouling treatment is required.

Once bio-fouling treatment is complete, the apparatus may be returned tothe submerged position by sequentially depressurizing the front and reartanks in reverse order from that used to float the apparatus. Once theair pressure is removed from the rear tanks, the weight of the apparatuswill cause water to displace the air in the rear tanks by entering theopenings located on the bottom side of each of the rear tanks. The rearend of the frame will then sink and rest on the water bottom to providestability to the frame. Next, the front tanks are depressurized todisplace the air in the front tanks with water. The front end will thensink to the water bottom, and the apparatus will be in the submergedposition.

The apparatus of the present disclosure is advantageous compared toknown shellfish aquaculture systems because it eliminates the timeconsuming manual labor involved with flipping containers fordesiccation. Because containers are not flipped manually, the capacityof a unit of containers can be increased substantially, typically fromless than 1,000 shellfish to greater than 10,000 shellfish. Theapparatus also reduces risks associated with manual flipping, such asfalls, drowning, hypothermia, wound infections, stings or bites fromjellyfish or other sea animals, or other similar risks.

Accordingly, one object of the present invention is to provide ashellfish aquaculture apparatus having pneumatic flotation control forsinking and floating the apparatus in order to facilitate all phases ofshellfish production and harvest. Another object of the presentinvention is to provide a method of bio-fouling treatment that does notrequire shellfish containers to be flipped.

DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is a top perspective view of a shellfish aquaculture apparatus inaccordance with the present disclosure.

FIG. 2 is a top perspective view of a shellfish aquaculture apparatus inaccordance with the present disclosure.

FIG. 3 is a top perspective view of a shellfish aquaculture apparatus inaccordance with the present disclosure.

FIG. 4 is a perspective view of a manifold for use with a shellfishaquaculture apparatus in accordance with the present disclosure.

FIG. 5 is a bottom perspective view of a shellfish aquaculture apparatusin accordance with the present disclosure.

FIG. 6 is a side view of a shellfish aquaculture apparatus being used inaccordance with the present disclosure.

FIG. 7 is a side view of a shellfish aquaculture apparatus being used inaccordance with the present disclosure.

FIG. 8 is a top plan view of a plurality shellfish aquacultureapparatuses being used in accordance with the present disclosure.

DETAILED DESCRIPTION

In the Summary above and in this Detailed Description, and the claimsbelow, and in the accompanying drawings, reference is made to particularfeatures, including method steps, of the invention. It is to beunderstood that the disclosure of the invention in this specificationincludes all possible combinations of such particular features. Forexample, where a particular feature is disclosed in the context of aparticular aspect or embodiment of the invention, or a particular claim,that feature can also be used, to the extent possible, in combinationwith/or in the context of other particular aspects of the embodiments ofthe invention, and in the invention generally.

The term “comprises” and grammatical equivalents thereof are used hereinto mean that other components, ingredients, steps, etc. are optionallypresent. For example, an article “comprising” components A, B, and C cancontain only components A, B, and C, or can contain not only componentsA, B, and C, but also one or more other components.

Where reference is made herein to a method comprising two or moredefined steps, the defined steps can be carried out in any order orsimultaneously (except where the context excludes that possibility), andthe method can include one or more other steps which are carried outbefore any of the defined steps, between two of the defined steps, orafter all the defined steps (except where the context excludes thatpossibility).

Turning now to the drawings, FIGS. 1-7 illustrate preferred embodimentsof a pneumatically controlled apparatus for shellfish aquaculture inaccordance with the present disclosure. As shown in FIG. 1, theapparatus comprises a frame 15 having a top side and a bottom side. Theframe 15 has at least one container 12 secured to the top side of theframe 15, and preferably has a plurality of containers 12 arranged inrows, as shown in FIG. 1. The containers 12 are designed for holdingshellfish such as oysters, clams, or mussels for aquaculture. Thecontainers 12 have a bottom and a continuous sidewall having a pluralityof holes therethrough to allow water to flow through the containers 12.As illustrated in FIGS. 1-3, the containers 12 are preferably meshbaskets 12. The mesh is small enough to contain shellfish but largeenough to allow sufficient amounts of water to flow through the basketsto provide an adequate food supply for the shellfish. The containers 12may also comprise an enclosed basket or cage having a top that can beopened to access the shellfish or closed to keep out predators when theapparatus is in use. Containers 12 may also be stacked vertically inorder to increase shellfish growing capacity. Stacked containers may besecured to adjacent containers or alternatively to a vertical rod,brackets, or similar support structure secured to the frame 15 of theapparatus to hold the containers in place. The containers 12 may besecured to the frame 15, to other containers, or to any other supportstructure utilizing any suitable fastener, including, but not limitedto, nuts and bolts, clips, rope, or wire. Each container 12 may bebolted to the frame 15 through the holes in the mesh of the container.

The plurality of containers 12 secured to the frame 15 make up a unit 10of containers 12 for farming shellfish. The unit 10 as shown in FIGS.1-3 comprises twenty individual containers 12 arranged in four rows offive containers 12 each and has a center walkway 50 to accommodate anon-board worker. This embodiment is illustrative only, and it should beunderstood that the present invention may comprise any number ofcontainers arranged in any manner, including stacking the containersvertically. Alternatively, the frame 15 itself may function as acontainer by adding a raised sidewall around the perimeter of the frame.

At least one tank 24 is secured to the bottom side of the frame 15, andpreferably a plurality of tanks 24 are secured to the frame 15. FIG. 5shows a bottom view of the apparatus and illustrates a preferredconfiguration of the tanks 24. In a preferred embodiment, the frame 15is generally rectangular and has four tanks 24 secured to the bottomside of the frame 15. The frame 15 has a first end and a second end,referred to herein as a front end 40 and a rear end 42, which arepreferably the short sides of the rectangular frame 15. The apparatuspreferably comprises four tanks 24 positioned at the corners of theframe 15. Two front tanks 24 a are positioned at the corners of thefront end 40, and two rear tanks 24 b are positioned at the corners ofthe rear end 42. As used herein, reference number 24 refers to all tanksgenerally, and reference numbers 24 a and 24 b refer specifically to thefront tanks and rear tanks, respectively.

The tanks 24 may be secured to the frame 15 utilizing any suitablefastener, including, but not limited to, nuts and bolts, clips, rope, orwire. Each tank 24 may optionally have eyes attached to the exterior ofthe tank and positioned such that the eyes may be used to bolt the tank24 to the frame 15.

Each tank 24 has a connection configured for connecting a fluid supplyline thereto. In a preferred embodiment, the connection is a nozzle 26to which a flexible air supply line 22 may be connected for supplyingair to each tank 24. Each tank 24 has a top side and a bottom side, andthe nozzle 26 is preferably located on the top side of each tank 24, asshown in FIG. 3, for connecting the air supply line 22 to the top of thetank 24. Each tank 24 also has an opening 25 located on the bottom sideof the tank 24, as shown in FIG. 5. The opening 25 allows water to fillthe tank 24 to displace air in the tank 24. The opening 25 is preferablyoffset from the center of the bottom of the tank 24, as shown in FIG. 5.In addition, the air supply nozzle 26 is preferably offset from thecenter of the top of the tank 24, as best seen in FIGS. 1-3. In apreferred embodiment, the opening 25 and the nozzle 26 of each tank 24are offset in opposite directions. For instance, the opening 25 on thebottom side of each tank 24 may be positioned nearer to the rear end 42of the frame 15, as shown in FIG. 5, and the nozzle 26 on the top sideof each tank 24 may be positioned nearer to the front end 40 of theframe 15, as seen in FIG. 1. This configuration may assist in thefloating and sinking of the apparatus, as discussed below.

Preferably, each air supply nozzle 26 comprises a bulkhead hose barbfitting located on the top centerline of each tank 24 about 12 inchesfrom the front end of the tank 24. Each of the openings 25 is preferablyabout two inches in diameter and located on the bottom centerline ofeach tank 24 about six inches from the rear end of the tank 24. As usedherein, the “front end of the tank” refers to the end of each tank 24nearer to the front end 40 of the frame 15, and the “rear end of thetank” refers to the end of each tank 24 nearer to the rear end 42 of theframe 15.

Preferably, the apparatus further comprises a manifold 14 configured forindividually controlling the flow of air to each of the tanks 24 via theair supply lines 22 connected to each air supply nozzle 26, as shown inFIGS. 1-2. FIG. 4 shows a detailed view of the manifold 14. The manifold14 and supply lines 22 shown in FIGS. 1-2 and FIGS. 6-7 may not be toscale and may be shown in a larger size with respect to the unit 10 ofcontainers 12 for ease of illustration. In a preferred embodiment, thesupply lines 22 may be standard one-quarter inch (¼″) diameter pneumaticair hoses.

The shellfish aquaculture apparatus is configured for use in twopositions: the floating position and the submerged position. The tanks24 are filled with air when in the floating position, as shown in FIG.6, and with water when in the submerged position, as shown in FIG. 7.When in the floating position, the containers 12 and the shellfishcontained therein are lifted above the surface of the water. Thecontainers 12 and shellfish can be held in this position for a period oftime sufficient to allow air desiccation in order to prevent theformation of biofilm on the containers 12 and shellfish, which is aprecursor to bio-fouling by barnacles or other unwanted organisms. Othershellfish husbandry activities such as stocking containers, sortingshellfish by size, and harvesting are also facilitated while theapparatus is in the floating position. Additionally, the apparatus canbe disconnected from moorings and towed away to avoid hazards or towedto a more favorable location for growth or acquisition of quality growthcharacteristics such as salinity. When in the submerged position, thetanks 24 rest on the water bottom and hold the containers 12 andshellfish contained therein off the water bottom to allow shellfishgrowth before harvesting.

As shown in FIG. 4, the manifold 14 has a connection nozzle 16 for aprimary air supply line 62 from a compressed air source 60 and a primaryair supply valve 18. The air source 60 is preferably a pressurized tank,as shown in FIGS. 6-7, which may be a SCUBA tank. The air source 60 mayalternatively be an air compressor. The air source 60 may have a supplyline 62 and associated valve 64 for shutting off airflow when connectingthe air source 60 to the manifold 14. The primary air supply valve 18allows a user to isolate the compressed air source 60 from the manifold14 by closing the valve 18 or to supply compressed air to the manifold14 by opening the valve 18. The manifold further comprises a pluralityof valves 20 for individually controlling the flow of air to each of thetanks 24. By supplying compressed air to the manifold 14 and opening avalve 20, an air supply line 22 will supply compressed air to acorresponding tank 24. If the tank 24 contains water, the water will bedisplaced by the air and pushed out of the opening 25 on the bottom sideof the tank 24. The displacement of the water by air will cause the tank24 to float. Displacing the water with air in all of the tanks 24 willfloat the entire frame 15 and the containers 12 secured thereto.

To move the apparatus from the submerged position, in which the tanks 24are filled with water, to the floating position, air is supplied to thetanks 24 in order to displace the water in the tanks 24 with air. Thedisplacement of water with air floats the frame 15 and the containers 12secured thereto, as shown in FIG. 6. First, a primary air supply line 62is connected to the connection nozzle 16 on the manifold 14 forsupplying compressed air to the tanks 24. The valves 20 on the manifold14 for controlling airflow to each of the tanks 24 are closed beforeopening the primary air supply valve 18 to supply compressed air to themanifold 14. Next, each of the valves 20 is opened to supply compressedair to each tank 24 via the air supply lines 22. As the pressurized airenters through the nozzle 26 on each tank 24, the air displaces thewater in the tanks 24 by pushing the water out of each respectiveopening 25 located on the bottom side of each tank 24. As the water isdisplaced by air, the frame 15 and shellfish containers 12 will rise tothe surface of the water. When the water has been substantiallydisplaced by air in each of the tanks 24, the apparatus will float onthe surface of the water such that the containers 12 and shellfishcontained therein are above the water surface, as shown in FIG. 6.

In a preferred embodiment, the process of filling the tanks 24 with airto displace the water is done in two steps. First, the two front tanks24 a are filled with air by opening the valves 20 for the supply lines22 connected to the front tanks 24 a. This step will cause the front end40 of the frame 15 to float while the rear end 42 of the frame 15 restson the water bottom. Next, the two rear tanks 24 b are filled with airby opening the valves 20 for the supply lines 22 connected to the reartanks 24 b in order to float the rear end 42 of the frame 15. Once theentire frame 15 is in the floating position, as shown in FIG. 6, all ofthe valves 20 for the air supply lines 22 may be closed, and the frame15 will remain in the floating position. Sequentially filling the front24 a and rear tanks 24 b with air improves the stability of theapparatus and reduces the risk of flipping the frame 15 and thecontainers holding shellfish during the process of filling the tanks 24with air to float the frame 15. The process of floating the apparatus isrepeated each time bio-fouling treatment is required.

As shown in FIGS. 1-2, the front end 40 and the rear end 42 preferablycorrespond to short sides of the rectangular frame 15. Sequentiallyfilling the front tanks 24 a followed by the rear tanks 24 b on theshort sides of the frame 15 improves the stability of the frame 15 whenfloating or submerging the apparatus. The long sides of the frame 15 arepreferably long enough so that the rear end 42 can rest on the waterbottom when the front end 40 is floating on the water surface, whichprovides stability to the frame 15 when floating or sinking the frame.Thus, it is preferable to float each end of the frame in a sequentialmanner. Because the openings 25 on the bottom side of each front tank 24a are positioned nearer to the rear end of each front tank 24 a, theamount of water displaced by air in the front tanks 24 a is increased byfirst floating the front end 40 of the frame 15 while the rear end 42rests on the water bottom. For the same reason, the openings 25 on thebottom side of each rear tank 24 b are also positioned nearer the rearend of the rear tanks 24 b. Once both ends of the frame 15 are floated,tanks 24 a and 24 b are generally level, which allows substantially allof the water in both sets of tanks 24 a, 24 b to be displaced by air.

Once bio-fouling treatment is complete, the apparatus may be returned tothe submerged position by sequentially depressurizing the front tanks 24a and the rear tanks 24 b in reverse order from that used to float theapparatus. First, the compressed air supply 60 is disconnected from themanifold 14 and the primary air supply valve 18 is opened to provide apressure relief point to relieve air pressure to the atmosphere. Next,the valves 20 for the supply lines 22 connected to the rear tanks 24 bare opened to depressurize the rear tanks 24 b. Once the air pressure isremoved from the rear tanks 24 b, the weight of the apparatus will causethe rear end 42 of the frame to sink, and water will enter the openings25 located on the bottom side of each of the rear tanks 24 b until theair in the rear tanks 24 b has been substantially displaced by water.The rear end 42 will then rest on the water bottom, thereby providingstability to the frame 15. Next, the valves 20 for the front end tanks24 a are opened to depressurize the front tanks 24 a and displace theair in the front tanks 24 a with water. The front end 40 will then sinkto the water bottom, and the apparatus will be in the submergedposition, as shown in FIG. 7.

FIGS. 1-3 illustrate a single unit 10 of shellfish containers 12 forease of illustration. As shown in FIG. 8, a plurality of individualunits 10 may be utilized to scale up a shellfish aquaculture operation.FIG. 8, which shows sixteen individual units 10, is illustrative only,and the number of units 10 may be increased or decreased according tothe desired capacity of the operation. In addition, the 2-by-8arrangement of units 10 shown in FIG. 8 is illustrative only. The units10 may be arranged in any suitable configuration designed to maximizeshellfish growth. In a preferred embodiment, the units 10 of containers12 are tethered to a structure such as pilings 30 driven into the waterbottom so that each unit 10 can be moved between the floating and thesubmerged positions while remaining tethered. In alternativeembodiments, temporary stakes, posts, or similar tethering structuresmay be used. In addition, any suitable anchoring devices, such as aconventional anchor, may be utilized to secure units in a location.Units 10 may also be tethered to piers, decks, or similar structures.For instance, existing piers may be utilized for shellfish production byinstalling multiple units 10 along the length of the pier.

Each individual unit 10 preferably has its own dedicated manifold 14 forsupplying compressed air to the tanks 24 of the unit 10. In a preferredembodiment, the manifold 14 for each unit is stored above the surface ofthe water, and the air supply lines 22 are sufficiently long enough toextend down to the tanks 24 when a unit 10 is in the submerged position.Each manifold 14 may have a float connected to it so that the manifold14 floats above its unit 10, or alternatively each manifold 14 may betied or otherwise secured to a piling 30 or other structure to store themanifold 14 out of the water when not in use. When using the apparatus,the front end 40 of the frame 15 is preferably positioned such that itis facing the prevailing seas, and the manifold 14 is preferablypositioned at the rear end 42 of the frame 15 for ease of use.

FIGS. 6-8 illustrate a floating barge 28 or boat adjacent to a unit 10of containers 12. The barge 28 may be used to hold the air source, suchas a compressed air tank 60 or a portable air compressor, so that a usercan transport the source of compressed air to each unit 10 to float theunit for bio-fouling treatment. Alternatively, another suitable gaseousfluid, such as nitrogen, may be utilized. When desiccation is complete,which typically takes about 24 hours, the barge 28 may be used to allowthe user to move from unit to unit to depressurize the tanks 24 via themanifolds 14 in order to return the units 10 to the submerged positionfor shellfish growth.

The top and bottom sides of the tanks 24 preferably have a generallyrectangular shape, as seen in FIG. 5. This shape allows air pressure tobe maintained inside the tanks 24 when the apparatus is in the floatingposition due to the openings 25 being positioned on the generallyhorizontal bottom side of each tank 24. The tanks 24 are sized such thatthey are sufficiently large enough to support the dead-load of the frame15 and payload of containerized shellfish and have sufficient reservebuoyancy to raise the frame 15 and payload above the surface of thewater body for desiccation. In addition, the tanks 24 are preferablylarge enough to lift the containers 12 and shellfish high enough out ofthe water to allow air desiccation during times of moderate wave action.This feature allows for timely, on-schedule air desiccation treatments,which reduces shellfish value losses due to bio-fouling defects. Thisfeature also reduces additional gear cleaning and maintenance costs dueto inadequate desiccation frequency, which can be caused by adverseweather conditions. Larger tanks 24 will also provide stability to theapparatus during moderate wave action and support the weight of anon-board worker. The worker can utilize the center walkway 50 betweenrows of containers 12 to perform various shellfish husbandry activitiessuch as stocking containers, size-sorting shellfish, grading shellfish,inspections to monitor the growth and quality of the stock, andharvesting.

In one preferred embodiment, the frame 15 of each unit 10 is abouttwelve feet in width and about sixteen feet in length. In addition, eachtank 24 is preferably about four feet by six feet by one foot(4′×6′×1′), with a volume of about 24 cubic feet. However, it should beunderstood that these dimensions may be varied according to the depth ofthe water, the desired shellfish capacity of the unit, and otherfactors.

The apparatus of the present disclosure is additionally advantageouscompared to known shellfish aquaculture systems because it eliminatesthe time consuming manual labor involved with flipping containers. Whenmanually flipping shellfish containers, the capacity of a unit ofcontainers is generally limited to about one thousand average sizedoysters due to weight consideration in a manual operation. Thepneumatically controlled apparatus may be capable of handling units ofshellfish containers holding significantly larger quantities and greaterweights of shellfish. Utilizing larger production units reduces laborfrom handling smaller units, thereby increasing the capacity of theoperation and reducing production costs. Larger units are also moreresilient to severe weather and to theft. The apparatus also reducesrisks associated with manual flipping, such as falls, drowning,hypothermia, wound infections, stings or bites from jellyfish or othersea animals, or other similar risks.

Additionally, the apparatus can be disconnected from moorings and towedaway to avoid hazards or towed to a more favorable location for growthor acquisition of quality growth characteristics such as salinity. Aunit of shellfish on board the apparatus can be relocated by floatingthe frame and towing it to a new area. The frame 15 will ride on thefour floating tanks 24 as it is towed. Once there, anchors may be setand the apparatus can be submerged in a controlled manner as previouslydescribed. The ease of relocation of the apparatus is advantageous overother known shellfish aquaculture systems, which typically requiretowing submerged cages of shellfish, which is a time consuming process,or loading heavy cages of shellfish onto barges for transport.

It is understood that versions of the invention may come in differentforms and embodiments. Additionally, it is understood that one of skillin the art would appreciate these various forms and embodiments asfalling within the scope of the invention as disclosed herein.

What is claimed is:
 1. A method of growing shellfish, said methodcomprising the steps of: providing a shellfish aquaculture apparatuscomprising: a tank having an opening located on a bottom side of thetank; a container for holding shellfish; and a compressed gas sourceconfigured to supply a gas to the tank via a fluid supply line connectedto the tank, wherein the container is positioned above a water surfacewhen the apparatus is in a floating position on the water surface withthe tank filled with gas; adding shellfish to the container; submergingthe apparatus in a body of water by filling the tank with water;allowing the apparatus to remain in a submerged position for a shellfishgrowth period; floating the apparatus by supplying gas to the tank sothat the gas displaces the water in the tank by forcing the water out ofthe opening located on the bottom side of the tank, thereby causing theapparatus to float with the container being held above the surface ofthe water; allowing the shellfish to remain above the surface of thewater for a shellfish desiccation period; and returning the apparatus tothe submerged position by refilling the tank with water to continue theshellfish growth period.
 2. The method of claim 1, wherein the step ofsubmerging the apparatus comprises: removing pressure from the tank sothat the water displaces the gas in the tank via water entering the tankthrough the opening located on the bottom side of the tank.
 3. Themethod of claim 1, wherein the apparatus comprises two tanks positionedat a first end of the apparatus and two tanks positioned at a second endof the apparatus.
 4. The method of claim 3, wherein the step of floatingthe apparatus comprises: supplying gas to the tanks positioned at thefirst end of the apparatus so that the gas displaces the water in thetanks at the first end of the apparatus by forcing the water out of theopenings located on the bottom sides of the tanks, thereby causing thefirst end of the apparatus to float while the second end of theapparatus remains submerged, and then supplying gas to the tankspositioned at the second end of the apparatus so that the gas displacesthe water in the tanks at the second end of the apparatus by forcing thewater out of the openings located on the bottom sides of the tanks,thereby causing the apparatus to float with the container holding theshellfish being held above the surface of the water.
 5. The method ofclaim 3, wherein the step of submerging the apparatus comprises:removing pressure from the tanks positioned at the second end of theapparatus so that water displaces the gas in the tanks at the second endof the apparatus via water entering the tanks through the openingslocated on the bottom sides of the tanks, thereby causing the second endof the apparatus to sink while the first end of the apparatus remainsfloating, and then removing pressure from the tanks positioned at thefirst end of the apparatus so that water displaces the gas in the tanksat the first end of the apparatus via water entering the tanks throughthe openings located on the bottom sides of the tanks, thereby causingthe first end of the apparatus to sink.
 6. The method of claim 3,wherein the apparatus further comprises a manifold configured to supplygas to each of the tanks.
 7. The method of claim 1, wherein theapparatus further comprises a manifold configured to supply gas to thetank.
 8. The method of claim 1, wherein the opening located on thebottom side of the tank is offset from the center of the tank.
 9. Themethod of claim 1, wherein the fluid supply line connected to the tankis connected to a top side of the tank.
 10. A method of controllingflotation of a shellfish aquaculture apparatus, said method comprisingthe steps of: providing a shellfish aquaculture apparatus, comprising: aframe having a top side and a bottom side; a container secured to thetop side of the frame; a plurality of tanks secured to the bottom sideof the frame, wherein each of the plurality of tanks has an openinglocated on a bottom side of each tank; a compressed gas source connectedto a manifold through a primary fluid supply line; and a plurality ofsecondary fluid supply lines individually connecting each respectivetank to the manifold, wherein the manifold comprises a plurality ofvalves arranged to individually control the flow of gas to eachrespective tank; submerging the apparatus in a body of water by fillingeach of the plurality of tanks with water; and supplying gas from thegas source through the manifold to each of the plurality of tanks sothat the gas displaces the water in each tank by forcing the water outof each tank through the opening located on the bottom side of eachtank, thereby causing the apparatus to float with the container beingheld above the surface of the water.
 11. The method of claim 10, whereinthe step of submerging the apparatus comprises: relieving pressure fromthe manifold to the atmosphere, and opening each of the plurality ofvalves to remove pressure from each of the plurality of tanks so thatwater displaces the gas in each tank via water entering each tankthrough the opening located on the bottom side of each tank, therebycausing the apparatus to sink.
 12. The method of claim 10, wherein theframe has a generally rectangular shape, wherein the apparatus comprisesfour tanks, and wherein each tank is positioned at one corner of theframe.
 13. The method of claim 10, wherein the opening located on thebottom side of each tank is offset from the center of the tank.
 14. Themethod of claim 10, wherein the secondary fluid supply lines connectedto each tank are each connected to a top side of each respective tank.15. A shellfish aquaculture apparatus, comprising: a tank having anopening located on a bottom side of the tank, a container for holdingshellfish, a compressed gas source configured to supply a gas to thetank via a fluid supply line connected to the tank, wherein thecontainer is positioned above a water surface when the apparatus is in afloating position on the water surface with the tank filled with gas.16. The apparatus of claim 15, further comprising a valve configured tocontrol the supply of gas to the tank.
 17. The apparatus of claim 15,further comprising a manifold configured to supply gas to the tank. 18.The apparatus of claim 15, wherein the container has a bottom and asidewall, wherein the bottom and the sidewall have a plurality of holestherethrough.
 19. The apparatus of claim 15, wherein the opening locatedon the bottom side of the tank is offset from the center of the tank.20. The apparatus of claim 15, wherein the fluid supply line isconnected to a top side of the tank.